1.6" Polished Schalenblende Slice - Poland
This 1.6" wide specimen was mined near Olkusz, Poland and contains a beautiful combination of sphalerite, galena and marcasite. It has been cut flat on both sides and polished to a glossy finish on one.
Schalenblende is a compact mass of sulfides, and can consist of galena, pyrite, wurtzite, marcasite and even sphalerite. It forms in concentric layers, and is believed to have formed by means of crystallization from a sulfide gel.
Marcasite is an iron sulfide mineral with the chemical formula FeS2. It is similar to pyrite in both its chemical composition and appearance, however it forms with a different crystal structure and is much more reactive to humidity. It is often found within sedimentary rock and hydrothermal deposits, and at one point was used for its sulfur content.
Galena is a lead based mineral that is in fact the primary ore of lead, and has been used for its lead content for thousands of years. Galena typically displays a gray metallic luster and forms cubes or octahedral crystals. The chemical composition of galena is PbS.
Sphalerite is a part of the sulfides group and typically exhibits a grey/black appearance due to high concentrations of impurities. When sphalerite is in it's purest state, the chemical composition is ZnS, and can display a gemmy transparent light tan/yellow color. This is one of the few minerals that can form crystals ranging anywhere between gemmy and transparent to opaque and metallic-like. Opaque or cloudy sphalerite tends to be most abundant, due to the ease of iron replacing zinc in the process of formation.